Push rod and method of its manufacture



N 1960 E. o. BURNARD EI'AL 2,960,080

PUSH ROD AND METHOD OF ITS MANUFACTURE Filed 001;. 29. 1958 IN VEN TORS EDWARD O. BURNARD & EAYMoA/D 72 READ 8 BY /6 g my I z K g /flflfpai AT TORN E Y5 PUSH ROD AND METHOD OF ITS MANUFACTURE Edward Octavius Burnard, Glandore, South Australia, and Raymond Thomas Read, Prospect, South Australia, Australia, assignors to Bundy Tubing Company, Detroit, Mich, a corporation of Michigan Filed Oct. 29, 1958, Ser. No. 770,496

20 Claims. (Cl. 123-90) The push rod of this invention may be used to inter connect a variety of movable members in various kinds of machines and the push rod is especially useful where one or more of the members ha a rotary component of motion. The present disclosure is made with reference to a push rod for operably connecting a valve lifter with a valve operating rocker arm in an internal combustion engine.

An object of the invention is to provide a simple, light weight, inexpensive push rod structure having improved operating characteristics. The invention generally contemplates a push rod formed by securing to each open end of a length of tube. an end piece having an exteriorly exposed rounded bearing surface for engaging a valve lifter or rocker arm. A further object of the invention is to provide a method of making such a push rod which generally comprises attaching the end pieces by fused metal connections to seats formed at the open ends of the tube. One form of the invention is illustrated in the accompanying drawings.

Figure 1 is a view partly in elevation and partly in section illustrating a push rod according to this invention in use.

Figure 2 is an enlarged view of the push rod with por tions broken away to illustrate structure at the ends.

Figure 3 is a enlarged perspective view of an end piece separate from the tube.

Figure 4 is an enlarged perspective view of another end piece separate from the tube.

Shown in Figure l is a push rod according to this invention operably interconnecting a valve lifter 12 and a valve operating rocker 14. Lifter 12 is raised and lowered by a cam 16 on a cam shaft 18 and the lifter moves in a guide 20 which may be formed in an engine block 22. Rocker 14 is rockably mounted on a shaft 24 with one arm 26 operably engageable with a valve (not shown) and with another arm 28 on the opposite side of shaft 24 engaged with the push rod. Rocker 14 may be spring biased in a conventional way for engagement against the push rod. Arm 28 has a projection with a preferably spherical surface 30 engageable within a cup shaped end piece 32 at one end of the push rod. Valve lifter 12 is provided with a recess 34 for receiving an end piece 36 at the other end of the push rod.

Push rod 10 is formed of a length of tube 38 which has open ends prior to the time when end pieces 32 and 36 are secured thereto. The tube may have any cross sectional shape although the round shape illustrated is suitable for most ptu'poses and facilitates economic manufacture. The tube may be of any suitable rigid type such as an extruded seamless tube or a rolled plural or single ply tube and may be made of any suitable material such as ferrous metal which will give it the requisite rigidity. An example of a suitable tube is a single ply rolled steel tube having a butt-welded longitudinal seam.

End piece 32 is cup shaped having rounded convex outer surface 39 and a rounded concave inner surface 40. Preferably end piece 32 is generally hemispherical in IL States Patent form with surface portions 39 and 40 being generally spherical. The cross dimension of cup element 32 is greater than that of the end of tube 38 to which it is secured.

End piece 36 is also preferably cup shaped having a rounded convex exterior surface 46 and a concave inner surface 48. Outer surface 46 is preferably generally spherical. End piece 36 has a surface portion 50 extend ing between surfaces 46 and 48 and a generally annular ridge or cusp 52 is formed where surface portions 48 and 50 intersect. The cross dimension of end piece 36 is greater than that of the end of tube 38 to which it is secured.

End pieces 32 and 36 are preferably formed of a relatively hard material such as a case hardened steel and may conveniently be formed by stamping. By this means the exposed surfaces 40 and 46 of the end pieces provide hard smooth bearing surfaces for engagement with valve lifter 12 and rocker arm 14. These surfaces are free of any machining marks and require minimal treatment subsequentto being stamped out and prior to use. End pieces 32 and 36 are secured to the ends of tube 38 by a fused metal connection such as by soldering, brazing, or welding.

In the form of the invention illustrated, end pieces 32 and 36 have been fastened to tube 38 by resistance welding. Exterior surface 39 of end piece 32 is engaged against the seat formed at the open end of the tube so that surface 39 and the seat engage in a generally annular region of contact. A welding current is then passed through the end piece and tube and the end piece and tube are urged toward each other to efiect the welding. During the Welding the walls defining the end of the tube are flared somewhat in a radial direction, thus increasing the width of the weld and providing a very sturdy joint between the end piece and tube. Fillets formed during the welding are illustrated at 54 and 56. g In the form of the invention illustrated end piece 32 and tube 38 are substantially concentric with the longitudinal axis of the tube and the central radius of end piece 32 substantially coincident.

7 then passed through end piece 46 and the tube and end piece are urged toward each other so that the heat and pressure effect the weld. During the welding the tube wall defining the end seat are softened and are upset in a bifurcate manner by cusp 52, thus thickening the weld region and providing a very sturdy joint between end piece 46 and the tube end. Fillets 58 and 60 are formed dur ing this welding. The initial engagement of cusp 52 against the tube end provides a small region of contact which facilitates initiation of the resistance welding. In the form of the invention illustrated, surface 46 of end piece 36 is substantially concentric with tube 38.

In use, convex spherical surface 46 is placed within recess 34 on valve lifter 12 and spherical portion 30 of rocker arm 28 is engaged Within spherical concavity 40 of end piece 32 at the upper end of the push rod. Surfaces 46 and 40 thus provide the bearing surfaces for engaging valve lifter 12 and rocket arm 28 respectively. Since surfaces '46 and 40 are substantially spherical push rod 10 may have random rotative orientation about its longitudinal axis. Where surfaces 46 and 40 are spherical as in the present illustration, the push rod is admirably adapted for interconnecting machine parts having rotary components of motion such as in the case of rocker arm 28. Where the cup defined by end piece 32 opens upwardly as in the illustration, it forms a container which retains lubricant to insure proper lubrication between surfaces 30 and 40. In applications where it is desired to prevent the flow of fluids through the interior of tube 38, the welds interconnecting the end pieces and tube are made continuous as in the present illustration and thus effectively seal off the tube interior. In other applications it may be desirable to provide for the flow of fluid such as lubricant through the tube interior and in this event openings may be provided through the end pieces as illustrated in dotted lines at 62 and 64 (Fig. 2).

The invention thus provides a push rod which is formed of a hollow tube and which is therefore relatively light weight so that the eificiency of an engine or machine in which the push rod is used will be increased.

The push rod has ready-made bearing surfaces, thus obviating the necessity of expensive machining operations. The invention also facilitates inexpensive manufacture since the tubing and the stampings forming the end pieces are relatively inexpensive, and since the open ends of the tube provide seats for engagement with the end pieces so that special machining or other preparation of the tube is minimized or obviated in providing the seats.

We claim:

1. Fush rod structure comprising, a tube having an end defining a seat having portions disposed at a non-perpendicular angle to the longitudinal extent of said tube, an element having a convex surface and a concave surface, one of said surfaces having portions disposed at a nonperpendicular angle to the longitudinal extent of said tube and engaging said portions of said seat, the other of said surfaces forming a rounded bearing surface adapted to engage a part of a machine with which said push rod is adapted to be used, and a fused metal connection connecting said portions of said one surface directly to said portions of said seat with said bearing surface disposed exteriorly of the tube for engagement with said machine part.

2. The combination defined in claim 1 wherein said concave and convex surfaces have different radii of curvature.

3. The combination defined in claim 1 wherein said convex and concave surfaces are generally concentric.

The combination defined in claim 1 wherein said concave and convex surfaces are concentric to the longitudinal axis of said tube 5. The combination defined in claim 1 wherein said concave and convex surfaces are generally spherical and generally concentric.

6. The push rod structure defined in claim 1 wherein said concave surface forms said bearing surface.

7. The push rod structure defined in claim 1 wherein said convex surface forms said bearing surface.

8. Push rod structure comprising, a tube having an end defining a generally annular seat having portions disposed at a non-perpendicular angle to the longitudinal extent of said tube, an element having generally the form of a spherical segment having an outer convex surface and an inner concave surface, said surfaces being substantially concentric, said outer convex surface having portions disposed at a non-perpendicular angle to the longitudinal extent of said tube and engaging said portions of said seat, said inner concave surface forming a generally spherical bearing surface adapted to engage a part of a machine with which said push rod is adapted to be used, and a fused metal connection connecting said portions of said outer convex surface directly to said portions of said seat with said concave bearing surface disposed exteriorly of the tube for engagement with said machine part.

9. Push rod structure comprising, a tube having an end defining a seat having portions disposed at a non-perpendicular angle to the longitudinal extent of said tube, an element having a convex surface and a concave surface, said element having a generally annular cusp extending around the periphery of said concave surface, said element having surface portions defining said cusp which extend at a non-perpendicular angle to the longitudinal extent of said tube and which engage with portions of said seat, a fused metal connection fastening said surface portions defining said cusp to said seat with said concave surface facing the tube interior, said convex surface forming a bearing surface adapted to engage a part of a machine with which said push rod is adapted to be used.

10. The combination defined in claim 9 wherein said element has peripheral side portions extending between said. concave and convex surfaces, said cusp being formed at the intersection of said peripheral portions and said concave surface.

11. Push rod structure comprising, a tube having two ends each defining a seat having portions disposed at a non-perpendicular angle to the longitudinal extent of said tube, a first element which is cup shaped and which has a wall, one side of which defines a concave surface having generally spherical shape and the other side of which has surface portions disposed at a non-perpendicular angle to the longitudinal extent of said tube and engaged against said portions of the seat at one end of the tube, a second element having a generally spherical convex surface portion and having other surface portions which intersect to form a ridge, said intersecting surface portions being disposed at a non-perpendicular angle to the longitudinal extent of said tube and engaging said seat portions of the other end of said tube, a fused metal connection fastening said surface portions of the first element to the seat at said one end of the tube with the concave surface of said first element being disposed exteriorly of the tube and forming a bearing surface, and a fused metal connection fastening said portions of said second element defining said ridge to said seat at said other end of said tube, said convex portion of said second element being disposed at the tube exterior and forming a bearing surface.

12. The method of forming a push rod which comprises, providing a tube having an open end portion forming a seat, providing a metal blank, subjecting said blank to deforming force and controlling said force so that the metal of said blank is deformed to provide a convex surface and a concave surface, one of said surfaces forming a rounded bearing surface adapted to engage a part of a machine with which said push rod is adapted to be used, engaging a portion of the other of said surfaces against said seat with said portion extending at a non-perpendicular angle to the longitudinal extent of said tube and with said bearing surface exposed exteriorly of the tube and While holding said portion of said other surface against said seat applying heat to the area of contact between said surface portion and said seat to provide a fused metal connection therebetween.

13. The method defined in claim 12 wherein a portion of said convex surface is engaged against and connected to said seat.

:14. The method defined in claim 12 wherein portions of said concave surface are engaged against and secured to said seat.

15. The method defined in claim 12 wherein said blank is deformed into a generally spherical segment having generally concentric inner and outer surfaces forming said concave and convex surfaces.

16. The method of providing a bearing surface at the tubular end of a push rod which comprises, forming a seat at said tubular end, providing an end piece having a wall, one side of which defines a concave surface and the other side of which defines a convex surface having a cross dimension greater than that of said seat, engaging against said seat a portion of said convex surface extending at a non-perpendicular angle to the longitudinal extent of said tube with said concave surface exposed exteriorly of the tube to provide a bearing surface for engagement with a machine part, and uniting said seat and the portions of said convex surface engaged thereby by a fused metal connection.

17. The method of forming a push rod which comprises, providing at the open end of a tube a generally annular seat, providing a hollow substantially hemispherical end piece having a concave inner surface and a convex outer surface, engaging against said seat a portion of said convex surface which extends at a non-perpendicular angle to the longitudinal extent of said tube with said concave surface opening exteriorly of the tube to provide a bearing surface for engaging a machine part, and while holding said portion of said convex surface against said seat applying heat to the region of contact therebetween to form a fused metal connection securing said end piece to said tube.

18. The method of forming a push rod which comprises, providing at the open end of a tube a seat, providing an end piece having a convex surface portion and another surface portion, said other surface portion including a cusp portion, engaging said cusp portion against said seat with surface portions defining the same extending at a non-perpendicular angle to the longitudinal extent of said tube and with said convex portion exposed at the exterior of the tube and providing a bearing surface for engagement with a machine part, and while holding said cusp portion against said seat, applying heat to the region of contact therebetween and urging said tube and end piece toward each other to form a fused metal connection therebetween.

19. The method of forming a push rod which comprises, providing at the open end of the tube a generally annular seat, providing an end piece of generally cup shape having a concave surface, a convex surface which is generally spherical and other surfaces which intersect said concave surface in a generally annular cusp, engaging said cusp against said seat so that they interengage in a generally annular region of contact and with surface portions defining said cusp disposed at a non-perpendicular angle to the longitudinal extent of said tube, applying pressure to said tube and end piece to urge them toward each other, and applying heat to the region of contact between said cusp and seat, said heat and pressure being suilicient to form a fused metal connection between said tube and end piece.

20. The method of forming a push rod which comprises, forming at the open end of a tube a seat, providing an end piece having a convex surface portion and other surface portions, said other surface portions intersecting to define an annular cusp, engaging said cusp against said seat with surface portions defining said cusp extending at a non-perpendicular angle to the direction of extent of said seat so that said cusp and seat interengage on a generally circular line contact, holding the cusp against the seat with said convex portion exposed at the exterior of the tube to provide a bearing surface for engagement with a machine part, and while so holding said cusp engaged against said seat, applying heat to the region of contact thcrebetween and urging the tube and end piece toward each other to form a fused metal connection therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 1,798,738 Hoern Mar. 31, 1931 2,434,080 Rosa Jan. 6, 1948 2,719,515 Archangeli Oct. 4, 1955 FOREIGN PATENTS 714,647 Great Britain Sept. 1, 1954 

